In general, the present invention relates to a heat pump system capable of providing heating and cooling requirements for residential and other applications. More particularly, the invention relates to a heat pump system providing such heating and cooling by employing a heat engine. More specifically, the invention relates to a heat pump system in which such a heat engine interacts with the remainder of the system in such a manner as to provide greatly improved efficiency and other performance characteristics.
Heat pumps have long been known and employed in the heating, ventilating, and air conditioning industry. A significant reason for the extensive use and focus of attention on heat pump systems is that the same components may be employed to effect both heating and cooling operations, whereas most other systems require a substantial number of separate equipment components for carrying out heating and cooling functions. Classically, heat pump systems employ a compressor which is operated by an electric motor to circulate refrigerant through a condenser which converts a gaseous form of the refrigerant to a liquid and an evaporator which absorbs heat from or imparts heat to an area to be cooled or heated, respectively.
For the most part, advancements in heat pump system technology have been directed to the development of improved working fluids and system components. In the case of working fluids, different refrigerants and particularly different fluorocarbon compounds have been developed which exhibit optimum performance characteristics in particular equipment or operating ranges. In regard to system components, efforts have been made to improve the operation and efficiency of the compressor, condenser, evaporator, and other ancillary components of these systems. However, due to the relatively advanced age and state of development of this technology, only minor improvements in operation and efficiency have been achieved through research and development efforts of this nature in recent years.
Attempts have been made to develop heat pumps which are heat driven. In this respect, engine driven and absorption type heat pumps represent examples of efforts of this type. Heat driven heat pumps of these types have not achieved commercial acceptance and recognition for a number of reasons. In general, devices of this nature tend to be highly complex systems having component elements which are both sophisticated and expensive. In addition, many of these systems contemplate the use of working fluids which are other than conventional refrigerants, such as ammonia or lithium bromide. Due to the fact that ammonia, for example, is considered to be a noxious gas, the use of nonconventional working fluids of this nature requires radically new and different capabilities and equipment with respect to installation, repair and service personnel that is not normally involved in the heating, ventilating, and air conditioning industry. With the technical limitations on working fluid and component improvements and the lack of commercial acceptance of heat driven heat pump systems, these systems have remained in essentially the same state of technological development for a substantial number of years.
Heat driven heat pumps employing heat engines and conventional working fluids have been developed but typically suffer from a number of disadvantages. For example, at the end of each power stroke of a heat engine piston, fluid at a high temperature of perhaps 300xc2x0 F. and a high pressure of perhaps 160 p.s.i. remains in the heat engine cylinder. When this fluid is discharged into a condenser there is a loss of a significant amount of kinetic and thermal energy, thereby rendering the overall system highly inefficient.
Another problem area in such heat driven heat pumps is that it is desirable to combine the heat engine and compressor within a single housing having a piston rod connecting the heat engine piston and the compressor piston. Since the optimum characteristics for the working fluids in the heat engine and the compressor are substantially different, it is necessary to employ two different refrigerants. Under these circumstances, it is a common problem to have the higher pressure working fluid eventually migrate through any seals into the lower pressure working fluid and thereby adversely alter the operating characteristics of the lower pressure working fluid.
A further difficulty in the design of heat engines is in providing a valve to effect shifting between high vapor pressure power stroke and exhaust stroke. When a conventional valve shifts, it allows vapor to blast into the cylinder so rapidly that it induces the entire heat pump to vibrate or shake violently, thereby shortening the life of the heat engine and being otherwise objectionable. Efforts to slow the valve shift motion have been unsuccessful because vapor will leak by the valve when it slowly passes from high vapor pressure position to the exhaust position.
Another notorious problem with heat engines is in effecting start-up if the unit has not been running and is cold. When the power section heat generator or evaporator first begins to deliver hot vapor to the power chamber of the heat engine, it condenses before it can drive the piston. Since there is a limited amount of working fluid in the heat generator it can run low on working fluid before the power chamber of the heat engine reaches operating temperature. This causes overheating of the heat generator and possible scorching of the working fluid, thereby requiring major servicing before the heat pump can resume normal operation.
As a result of various of the above factors or combinations thereof, heat driven heat pump systems have not achieved any extent of commercial acceptance.
Therefore, an object of the present invention is to provide a heat pump system which may be exclusively heat driven. Another object of the invention is to provide such a heat pump system wherein the working fluid in a power section is vaporized in a heat generator or evaporator by any heat source, such as a high efficiency gas boiler. Still another object of the invention is to provide such a heat pump system that lends itself to alternate energy assistance or powering, such as the incorporation of solar, biogas or other sources available to create heat energy.
Another object of the present invention is to provide a heat pump system wherein the heat engine of the power section and the compressor of the compressor section constitute a combined or consolidated unit. Another object of the invention is to provide such a combined heat engine and compressor assembly which does not require a fluid interconnection between the engine and the compressor. Still another object of the present invention is to provide such a combined heat engine and compressor assembly wherein the pistons of the heat engine and the compressor are mechanically interconnected. Yet another object of the present invention is to provide such a combined heat engine and compressor assembly which prevents migration of working fluid from the high pressure side to the low pressure side by employing two spaced rolling diaphragm seals having pressurized water therebetween, both the diaphragms and the water combining to constitute an effective barrier to refrigerant migration.
A further object of the present invention is to provide a heat pump system wherein a unique valve controls the ingress and egress of fluids into the chamber housing the heat engine piston. Another object of the invention is to provide such a valve which provides transition between the power and exhaust strokes by smooth, positive motion which prevents any bleedover when the piston power chamber is shifted between exhaust and high pressure operating conditions. Still another object of the present invention is to provide such a valve which does not require either electrical or mechanical shifting mechanisms to effect operation of the valve.
Another object of the present invention is to provide a heat pump system which automatically solves cold startup problems normally encountered when a system has not been running and the heat engine is at ambient temperature. Another object of the present invention is to provide a preheat chamber adjacent to the cylinder of the heat engine which receives vapor from the heat generator and returns condensate to the heat generator until the heat engine cylinder is sufficiently hot, such that the system can be started with the hot vapor immediately driving the piston in a power stroke. A further object of the invention is to provide such a preheat chamber which is an annular column surrounding a ceramic cylinder wall which is heated by conduction from the hot vapor in the annular preheat chamber. Yet a further object of the invention is to provide such a preheat chamber which is disposed above the heat generator producing the hot vapor working fluid which is arranged such that any condensate initially forming in the preheat chamber is returned solely by gravity to the heat generator for reconversion to hot vapor.
Still a further object of the present invention is to provide a heat pump system wherein kinetic energy from the exhaust at the end of the power stroke of the heat engine piston is employed to assist the power stroke. Another object of the invention is to employ the exhaust from the heat engine to operate a turbine driving a pump which creates a vacuum condition on the back side of the heat engine piston to assist in the power stroke of the heat engine piston. A further object of the present invention is to provide a turbo impeller and pump arrangement which may be energized solely by vapor exiting the heat engine chamber or which can be supplemented by an electric motor or solar powered motor to further increase operating efficiency of the heat engine.
Yet a further object of the invention is to provide such a heat pump system wherein all moving parts and sealing areas can be constructed of relatively low-cost ceramic materials due to the fact that the entire system operates at relatively low temperatures. A further object of the present invention is provide such a heat pump system wherein the ceramic materials used for the moving parts and sealing areas increase efficiency of the heat pump system by providing for fluid-tight but low friction sliding engagement. A further object of the invention is to provide such a heat pump system which may employ a working fluid in the heat engine section which requires substantially less heat per hour for conversion to vapor, thus representing a substantial increase in overall efficiency of the heat pump system.
Yet still another object of the invention is to provide a heat pump system wherein a condensate pump is used to transfer working fluid from the condenser to the heat generator in the heat engine system. A further object of the invention is to provide a heat pump system wherein the condensate pump is a piston-driven condensate pump. A further object of the invention is to provide a heat pump system wherein the piston of the piston-driven condensate pump is attached to the piston of the heat engine, and is thereby driven according to the movement of the compressor and heat engine pistons.
Yet still a further object of the invention is to provide a heat pump system which can readily employ a variety of heat exchangers and other design features which permit further optimizing the overall efficiency of both the heat engine system and the compressor system. A further object of the invention is provide a heat pump system wherein the heat exchanger is a triple-tube type and is used to heat water such as that contained in a swimming pool, hot water heater or the like. A further object of the invention is provide a heat pump system wherein the refrigerant from the compressor and the working fluid from the heat engine are directed to the triple-tube heat exchanger. A further object of the invention is provide a heat pump system wherein heat from the refrigerant and from the working fluid is transferred to water from the swimming pool, hot water heater or the like.
In general, the present invention contemplates a heat pump system including a heat generator, a heat engine supplied with heat engine working fluid by the heat generator having a heat engine cylinder chamber, a heat engine piston, and a heat engine piston rod, a preheating chamber employing the heat engine working fluid to heat the heat engine cylinder chamber, a condensate pump supplying said heat generator with heat engine working fluid, a compressor driven by the heat engine employing compressor working fluid having a compressor cylinder chamber, a compressor piston, and a compressor piston rod, a spacer separating and joining the heat engine piston rod and the compressor piston rod, a sealing assembly associated with the spacer separating the heat engine working fluid and the compressor working fluid, and a valve assembly communicating with the heat engine cylinder chamber and controlling the ingress and egress of heat engine working fluid to the heat engine.